| Re: IDL objects and names [message #34068 is a reply to message #33970] |
Wed, 12 February 2003 05:33  |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Sebastian (s@visita2.die.upm.es) writes:
> when I create an IDL object, I can give it a name, like
> oImg = OBJ_NEW('IDLgrImage',Name='myImage').
>
> I thought that this might be nice for debugging, but neither help nor
> heap_gc,/VERBOSE display the names of the objects.
>
> Is there a way to make heap_gc and help display the names?
> Are there any other techniques to get more info about objects that are
> removed by heap_gc?
> I mean, with an heap_gc,/VERBOSE output like
> <ObjHeapVar37> STRUCT = -> IDLGRPALETTE Array[1]
> I can't do much when I have a lot of IDLgrPalettes around.
Yes, it can be discouraging after you write your first couple
of object graphics programs to get that e-mail from an important
colleague suggesting that your programs might be leaking a bit
of memory. Leaking!? More like a memory sieve! :-(
What to do with that huge long list of objects left on the
heap? First, of course, is to start paying more attention
to memory management as you write your programs. You will
do this automatically in a few more weeks. Human beings
can only take so much pain. :-)
The second step is to try to figure out where these leaks
are coming from. If you have had the foresight to name
your objects, you are in pretty good shape. First, you
will have to recover the objects. Here is an example
using two palette objects:
pal1 = Obj_New('IDLgrPalette', Name='GrayScale')
pal2 = Obj_New('IDLgrPalette', Name='Std Gamma')
pal2 -> LoadCT, 5
pal1 = 0
pal2 = 0
Ok, now my palettes are lost on the heap:
IDL> Help, /Heap
Heap Variables:
# Pointer: 2
# Object : 2
<ObjHeapVar2> STRUCT = -> IDLGRPALETTE Array[1]
<ObjHeapVar3> STRUCT = -> IDLGRPALETTE Array[1]
<PtrHeapVar4> BYTE = Array[768]
<PtrHeapVar5> BYTE = Array[768]
Notice there are pointers, too, probably associated with the
palettes. (At least I *hope* they are!)
The first step is to recover the palette objects. We can do
this with OBJ_VALID and no arguments:
IDL> lostObjects = Obj_Valid()
IDL> Help, lostObjects
LOSTOBJECTS OBJREF = Array[2]
Now we can just get and print the names of the objects:
IDL> FOR j=0,N_Elements(lostObjects)-1 DO BEGIN $
lostObjects[j] -> GetProperty, Name=theName &$
Print, theName & ENDFOR
GrayScale
Std Gamma
Or, because that darn FOR loop is so hard to write, I just
might add a PrintName method to the IDLgrPalette object.
PRO IDLgrPalette::PrintName
Print, self.name
END
Save this as idlgrpalette__printname.pro. Then, just type
this:
IDL> FOR j=0,N_Elements(lostObjects)-1 DO lostObjects[j] -> PrintName
GrayScale
Std Gamma
Now, maybe, you have some clue about where these darn things come
from. :-)
Cheers,
David
P.S. Of course, you must also destroy these objects.
IDL> Obj_Destroy, lostObjects
IDL> Help, /Heap
Heap Variables:
# Pointer: 0
# Object : 0
Hooray, we got those pesky pointers, too! :-)
--
David W. Fanning, Ph.D.
Fanning Software Consulting, Inc.
Phone: 970-221-0438, E-mail: david@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155
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